Vertical lift bridge



April 1 E. E. HOWARD VEIIFPI'IIICAI.) LIFT BRIDGE Filed June 9, 1930INVENTOR. f/ llcsfzf flan 0rd Q/Q 8 ATTORN Patented Apr. 26, 1932' TED-STATES ERNEST E; HOWARD, on KANSAS orrxnrssounr VERTiCAL. ILIFr BRIDGEApplication filed June 9, 1930. seri l N 459,854.

while the spanis suspendedin a horizontal position. v

Fig. 1 1s a diagrammatc view of one of the supporting towers, ineludinga portion of the lift span. Fig. 2 is a detail of a modified form ofbelt tightener. V r

In orderto simplify the explanation. and

understanding ofthe invention, the mechanism on but one of the towerswill be explained as the towersare identical in operationandconstruction. The numeratldesignates the lift span, the numerals 2the towers which support the span. v

The span is suspended by suitablejflexible supporting meanspreferablysteel wire ropes such as are shown at 3. These wire ropestively mounted on the top ofthetowers which towers may be constructed ofsteeLtimber, reinforced concrete, or-other material; The flexible wireropes 3 are attached to the-lift span land also to acounterweightt. jThe counterweight on each tower is equal approximately in Weight to onehalf of the weight of the span so that the counterweights balancetheweight of the span;

For operating the-span there are provided at the'top of each towerdriving pulleys6 and 6A which are connected by trains of gears andpinions 7, 8, 9, 1O andvll to the main sheaves on the tower. The pulley6 is mounted upon the shaft 12. upon -whichis also mounted the pinion 8.The pulley 6a is mounted upon the shaft 120 upon which is alsomountedthe pinion 7. The pinions 7 and 8 mesh with the gear wheel 9.This latter 45 gear is mounted upon the shaft 13, which also carriespinions 10,m.eshing with'the large gears 11, mounted upon" the shaftscarrying the sheaves 4. One drive pulley 600 through a r flexible cable29a and gear train 7,9, 10' and 2111 provides for rotation in onedirection a and and in anopposite direction. In other' words the" runover the main supporting sheaves 4, rota the other pulley [c with itsflexible cable 122 gear train 8, 9,. 10 and 11' for rotation.

drive provided through pulley 6w raises the span whilethe'drive throughthefopposite fib pulley 6 lowers the; span; I The reversal of the drivefor raisingand lowering the span by means of the flexible cables isproduced' b themanner in whichthe 'cables22 and 29 i v are made topassbeneath the separateisetsof idler pulleys so that one; the mmeeaas hdfrom over the top of the drive 'pull yfia under the pulley21,-whilejthe1cableZZis'iled V 7 from ,over' the top 50f the drivepulley 6"to pass over 'thexpulley 18, mounted .onshaft 17;. Thereversal; of one of the drive pulleys could also ,be pro'ducedfbyinterp-osing;-;an" intermediate'gear between either ofthe gears 7 and8Iwhich mesh with the gear 9.

It will be observed thatif one drive'pulley m on the topof each towerislsimultaneously rotated at the same speed they willicausethe mainsheaves 4oniboth towers to rotatesimultaneously and thus lift thesuspended span;-

and lower the counterweight, orv byreversing 76 the direction by,operation of'the other' pa-ir of drive pulleys the counterweights arelifted and the span. lowered. In order to provide asuitabl'e.sour'ceofpowerto eifectthe operaftion, there is placed on the lift spana motor 80 engine or other' suitable source'ofpowerdesi'gnatedby'thenumeral 14. .On'the shaftof the-inotor.ismounteda pinion 1 5, meshing Jwith thefgear 16 which, in turn, is carriedby thetransverse shaft 17 Onthis transverse shaft 17are a plurality of pulleys 18,". 19,'2O

and 21; or a grooveddrum.. Flexibledri'v- 'ing means, preferably steelwire mpg runs upon the'the pulleys; the drive tram the pulleys 18 and 21"s transmitted'to the tower mechanism which is hereinfexplai'ned *whilethe pulleys 19 and 20 transmit the power to the drive mechanism mounteduponfthfe qpposite tower which is identical in operation o with thedrive explained p 7, H o Two 7 parts of thefleXible-"wire 'rope',2 2which passes over the? pulley. 18- are carried; out to the endsiof thelift span and there pass under idler" sheaves 23, which are'rotativelymounted on the lift span by means ofastandcombine with the ard orsupport 24, These two parts are then carried upwardly one part passingover the drive pulley 6, the other part over idler pulleys 25, 26, and27, and under idler pulley 23, terminating as the part which passes overthe top of the idler pulley 6. In a similar manner, the two parts of thewire rope 29 pass under the idler pulleys 30' and 31, the upperpartpassing over the drive pulley 6A and the lower part over the idlerpulleys 32, 33 and 34, and under .theidler pulley 35. to part passingover the drive pulley 6A. I 1

It is evident that, if the liftspan begins to rise, the distance betweenthe drive pulleys on the liftspanand the corresponding drive I pulleyson the top of th-e'tower will shorten the amount of the lift of thespan. To

compensate for this shortening, the endless .flexlble wire ropes arepassed under the 1dler sheaves 35 which are mounted upon the maincounterweight-.5 or, as shown in the modified construction 1n Fig. 2, tosupplementary counterwe ghts 5a, which are raised and loweredin wellsformed in the main counterweight'o'r otherwise independent of the maincounterweight. From these idler sheaves 28 and 35. one side of theflexible ropes are passed 7 over suitable idler sheaves movably mounted9 so asto provide for tension in the fiexi le ropes'and to carry oneside of each flexible rope inv such a manner that it may be con- .tinuedback to the drive pulley on the lift s an. 7

In Fig. 1, at points37 and 38 on the coun terweight 5 are, pivotedweighted arms, one extension of thearms carrying the weights 39 theother arm extens ons carrying the idler pulleys 27 and 34. The pivotedweights 3.9 keep a constant tension .upon the driving fropes 22 and 29.

In addition to compensating-for the difference in distance between thedrive pulleys on the lift span and the drive pulleys onthe towers, theidler sheaves 28 and 35 and their counterweights afford a means formaintaining tension in the flexible driving ropes. As suggested, theprovision for maintaining the tightness of these flexible belts ,orropes .c an be made by suitable counterweights 5a. .One means ofproviding for flexible rope tension is shown in Fig. 1 and a modifiedprovision is shown-in Fig. 2. In place of the two one or more pairs foreach tower.

types shown, springs may be providedto take the, place of the smallcounterweights or similarknown mechanical means.

The flexibledriving ropes are provided in A single driving. rope hasbeen shown in order to simplifythe disclosure and explanation) I In,thedrawings,t-he flexible driving rope 22 is arranged to operate the drivepulley 6 when, the driving pulley on thespan is moving in a clockwisedirection as indicated by the arrow on the flexible belt. It will beobserved that this belt provides a continuous connection from the top ofthe drive pulley on the span to the drive pulley on the tower, andengages both these drive pulleys sufliciently to provide the necessaryfriction for operation. The means for maintaining tightthe meansformaintaining tension in the v driving rope 29 is carried on the oppositepart of the rope from the driving part. I

Thereisthusprovided from the driving pulleys 18' and 21 on the lift spana direct connection through the tightside or part of thevfiexible ropesfor either direction of rotation'through the'drivi'ngpulleys 6 and 6a onthe tower. Corresponding flexible belts or ropes are provided throughsimilar driving pulleys on the drive shaft .of the lift span runningover similar driven pulleys mounted on the opposite tower.

' It is evident by proper adjustment of these flexible drivingropes'rotation of the drive shafton the lift span-will cause similar andequal rotation of the main sheaves on both towers, as the sizes of thepulleys and the driving connections are identical on both 1 towers,providing thereby for the lifting and lowering of the lift span, evenlyand uniformly.

In practice, the four drive pulleys 18, 19, 20 and 21 inclusive on thelift span can be constructed as separate pulleys or as a single drumwith separate grooves and the flexible belts or ropes for raising andlowering the lift span may be in two or more pairs for each tower. v p aI In previous practice with lift spans where the operating machinery isplaced on the tops of thetowers, it has been necessary to provide aseparate motor orsource of power on the top of each tower. The presentdesign 1 provides for the operation of the machinery on the tops of bothtowers simultaneously and synchronously from the single source of poweron, the lift span. .Where, a separate source of'power is required on thetop of each tower internal combustion engines cannot be employed, butwith the single source of power on the lift span the power may besupplied by an internal combustion engine.

Other advantages of the design are readily apparent. In the first place,it will be noted that substantially all of the machinery and weight isremoved from the lift span and placed upon the towers, the motor anddriving pulleys and thedeflector sheaves being are required on the topof each tower no such substantially the only machinery left upon thespan. Furthermore, by positioning the driven machinery on the separatetowers and driving from a single source on the lift span, there is anequalization and uniform distribution of transmitted power so that themachinery on both towers operates alike and is accurately synchronized.

In the present design, by the use of the tightening devices, there ismaintained a constant tension upon the driving belts regardless of thevarying distances of the pulleys on the lift span, and the towers. Thiscompensation is brought about by the idler sheaves and supplementarycounter-weights.

Furthermore, it is throught to be novel practice to raise and lower thelift span from a single source of power positioned onthe lift spanthrough flexible endless ropes or belts transmitting power to operatethe -mainsheaves on the tops of the two towers.

Suitable brakes, not shown or-described, of simple and positivecharacter for hand operation can be provided on the driving shaft on thelift spanto control the movement. Where separate motors or sourcesofpower simple and positive brakes can be used.

I claim as my invention: 1 1. In a vertical lift span bridge,the'c'ombination with supporting towers, of a lift span, a source ofpower positioned on the lift span only, driving means on the lift spanand driven means on the towers, flexible coni nections between thedriving and driven means, whereby when said driving means is actuatedsaid lift span will be operated;

2. In a vertical lift span bridge, theicombination with supportingtowers, of a, lift span, a source, of powerpositionedon the lift spanonly, driving means on the lift span and driven means on the towers,flexible conand driven means on the towers, endless flexible connectionsbetween the driving means and I driven means, having driving partswhereby said lift span is operated when said driving means is actuatedand return parts and means interposed in the return parts formaintaining tension in the return parts of the flexible connections andfor taking up any stretch of the flexible connections.

5 In a vertical lift span bridge, the combination which includes thespan and sup-.

porting towers, a single power source and driving means on the span,driven means on the towers and flexible connections therebetween,whereby said lift span is operated when said driving means is actuated.6. In a vertical lift span bridge, the com-.

binationwhich includes thespan and supporting towers, a single powersource and driving means on the span, driven means on the towers andendless flexible connections therebetween,whereby-saidlift span is op-''erated .whensaid driving means is actuated and means for compensatingfor the vari-' ations in distance between the driving and driven means.i

In testimony whereofI. affix my signature.

' ERNEST E; HOWARD.

nections between the driving and driven means, whereby when said drivingmeansis actuated said lift span will beoperated, and

means for compensating for the variation in the distance betweenthedriving means on the lift span and the driven means on the towers. Z

3. In a verticallift span bridge, the combination with supportingtowers, of a lift.

span, a source of power positioned on'the lift span only, driving meanson the lift s an and driven means on the towers, endless exibleconnections between the driving and driven means having driving partsand return parts whereby said lift span is operated when said drivingmeans is actuated and means interposed in the return parts of theflexible means for compensating for the variatlon 1n dlstance betweenthe driving and driven means.

4. In a vertical lift span bridge, the com- I bination with supportingtowers, of a lift span, a source of powerpositioned on the lift spanonly, driving means on the lift span

